The present invention relates to powered roller conveyors, and particularly such conveyors which comprise a plurality of independently driveable accumulating zones. More specifically, the invention concerns the provision of improved friction wheel drive means for powering the load carrying rollers in any zone of the conveyor, independently of all other zones, while utilizing a single power source for the entire conveyor.
Important objects of the present invention reside in the provision of improved roller conveyor drive means: which may be bi-directional in operation; which is operable to permit accumulation independently in any one or more zones of the conveyor utilizing a common power source for the entire conveyor; which permits "zero pressure" accumulation whereby controlled spacing is maintained between the articles conveyed (thus eliminating storage line pressure between the articles); which may be controlled to permit conveyed articles to be released singularly or in a train; which can be used as a merger or sorting main line and still retain full accumulation features; which is readily suited for use with conventionally used article sensors and other standard hardware in accordance with established techniques; which has a relatively low profile and may be of any practical width; which in certain embodiments may permit "free wheeling" of the load carrying rollers when nonpowered, whereby gravity or other conveying may take place in either direction in the nonpowered zone (i.e., no "free wheeling" upon power failure), or which in other embodiments may permit automatic breaking of the load carrying rollers when nonpowered; which is adapted for use on both belt powered and chain powered conveyors and may be easily adapted for different length accumulating zones and/or roller spacing and roller size; which may have a variety of zone lengths in a single conveyor; which incorporates individual drive modules which may be easily added to an existing roller conveyor to provide an accumulating function; which is capable of transmitting relatively high and yet adjustable drive forces with relatively modest actuating forces; which is capable of having zone lengths easily changed after installation if zone length requirements should change; and, which is relatively simple in construction, utilizing primarily standard readily available conveyor components and having a fully enclosed drive.
Another important object of the present invention resides in the provision of a belt powered accumulating roller conveyor having a plurality of modular type drive units of identical construction which may be individually hung wholly or partially from the load carrying roller shafts wherever desired throughout the length of the conveyor, whereby they are always properly located with respect to the load carrying rollers to be driven thereby, and may be varied in number depending on the forces required in a given application. A related object concerns the provision of such a conveyor having means for maintaining constant belt length regardless of the number of zones being powered at any given time.
These and other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.